The other day, I caught a spider I didn’t recognize — this is not at all uncommon, I’m an amateur trying to learn — and I had to post it on iNaturalist to get it identified. It was a Pirate Spider! I’d never seen one before. If you’re not familiar with pirate spiders, they’ve earned their name: they are predators of spiders that board other spider’s webs and kill the owner and loot her of her life, arrrr.
Pirate spiders are members of the spider group that includes all the “orb weavers” – those that make the prototypical, circular webs we are all familiar with – but they do not make webs.
In fact, they have lost the ability. They can still produce silk, which they use to build egg sacs and wrap prey. But they are anatomically incapable of spinning a web. The number of silk “spigots” on their spinnerets is dramatically small compared to their relatives.
Instead, they invade the webs of other spiders, in a bid to lure and then kill the hapless architect. Gently, they pluck the strings of the web, enticing the host to approach.
Once the host spider has ventured close enough, the pirate makes its move.
First, it encloses its duped prey within its two enormous front legs. These are fringed with massive spines, called “macrosetae”, which they use to trap the host within a prison-like basket.
Then, the final move: the pirate bites its prey and uses its fangs to inject a powerful venom that instantly immobilises it.
I include my photo below the fold.
The diagnostic feature, I take it, is the row of spines all angled in the same direction on the forelegs.
Doesn’t there seem to be something intuitively wrong or repugnant with this spider’s modus operandi? Probably shows why we shouldn’t impose moral evaluations on nature. On the flip side should we positively evaluate species that do stuff we see demonstrating positive cooperative traits? Or even see crocodilians more positively as they exhibit the maternal care that sea turtles lack? Or long term pair bonding in birds and mammals who are warm and fuzzy as we are? I’m vaguely recalling Doesn’t there seem to be something intuitively wrong or repugnant with this spider’s modus operandi? Probably shows why we shouldn’t impose moral evaluations on nature. On the flip side should we positively evaluate species that do stuff we see demonstrating positive cooperative traits? Or even see crocodilians more positively as they exhibit the maternal care that sea turtles lack? Or long term pair bonding in birds and mammals who are warm and fuzzly as we are? I’m vaguely recalling Churchland’s contrast of voles which may have stemmed partly on hormones (oxytocin and vasopressin)? Churchland’s contrast of voles which may have stemmed partly on hormones (oxytocin and vasopressin) and how I could connect more with the mode of the more monogamous species because moral upbringing.
Wow something went wrong with that post. Try this:
Doesn’t there seem to be something intuitively wrong or repugnant with this spider’s modus operandi? Probably shows why we shouldn’t impose moral evaluations on nature. On the flip side should we positively evaluate species that do stuff we see demonstrating positive cooperative traits? Or even see crocodilians more positively as they exhibit the maternal care that sea turtles lack? Or long term pair bonding in birds and mammals who are warm and fuzzly as we are? I’m vaguely recalling Churchland’s contrast of voles which may have stemmed partly on hormones (oxytocin and vasopressin)?
There’s nothing any more repugnant about this spider’s behavior than the behavior of human non-vegetarians. “Intuition” is just a word for “my personal biases”.
I would say, if we’re assigning moral values to the actions of arthropods, that the ichneumon wasp is far more disturbing than a spider that wears funny hats and goes “Arrr, matey!” to other spiders.
How repugnant are we who entrap and fatten up free wild yeast and enslave them to fluff up our sourdough before roasting them alive in the oven? ;)
That reminds me of a joke-
What does a pirate say on his 80th birthday?
“Aye Matey!”
It’s no crueller than fishing. Besides, you can’t assign moral value to the actions of a non-human animal.
the reaction is real at least for me but it is very arbitrary and unevenly stimulated by unrecognized personal biases.
it took me some amount of time to not react seeing a new to me species of rather large and very fast moving centipede I found living in my garden.
I knew what they must be after but the reaction was negative anyway
black widows on the other hand are only a surprise in unexpected places.
uncle frogy
Aren’t this type of spider also called Portia Spiders?
I was listening to Pinker (grrrr) address morality in The Blank Slate and he was talking about Haidt’s moral dumbfounding work which may have preloaded me on the intuitionism, but at an intuitive level the spider eating another spider and taking their hard work (the web) just seems wrong.
Yes intuition can be bad and I was being facetious to make a larger point about not reading stuff into nature even when it aligns positively with our intuitions (later in my post). Also along lines of Kahneman‘s two systems gut intuition could be all we got. The deliberative reason part helps rationalize our kneejerks in after the fact fancy terms.
Also the Moore we got the fallacy I implicitly invoked from was an ethical intuitionist as was WD Ross so there’s a tradition there.
So if there is a Pirate Spider, then is there also a Flying Dutchman Spider? Forever drifting the currents with its draglines of silk, a portent of doom for all who glimpse it, said by many to be desperate to contact its Cretaceous friends with addresses in Gondwana and Pangaea.
We need to all set up big arachnid terraria and raise vast hordes of Mimetidae, to fight global warming.
May you be touched by his Noodly Appendage!
hemidactylus:
I agree that we ought not to impose our morality on nature’s critters, I can’t help but wonder whether a psychoanalyst might be informed about the psyche of some human by some strongly held opinions of various critters; e.g. a ‘rabid’ fan of say, a pirate spider over a normal web spinner. “What a loser, wasting all that time building that ornate web when she could just take one over without all that work!”
Might such strong opinions be diagnostic of certain personality types/disorders?
(I’m not talking about casual reactions).
The market for eye patches (& wooden legs) must be huge!
@14- Colin J
That’s funny.
Trying to envision a swordfight between spiders. Would they use more than two because they can? And why rely on a sailing ship when a silk parachute would suffice?
When I was brushing my teeth this morning a small black speck caught my eye. Not sure if it was parachuting or rappelling from my head but a very tiny spider wound up plopping down into the middle of a puddle on my countertop. At that point I wondered if it had serious regrets concerning recent decisions it made. But it managed to get itself to a dry spot. If I tried to help I would have killed it inadvertently due to fragility.
“What’s a pirate spider’s favourite letter?”
“R…”
“Oh, they like the R. But they love the C.”